Vacuum preventer



May 28, 1940. v. w. STRCDE VACUUM PREVENTER Filed Jan. 8, 19258 INVENTORV/ TOR WSTRQDE.

FJLIEJYI ATTORNEY Patented May 28, 1940 UNITED STATES PATENT OFFICE 9Claims.

This invention relates to vacuum preventers for receptacles utilized forholding fluids under pressure, of which a water distribution piping isan example, where a vacuum of any degree will be detrimental.

To avoid cross-connections incident to plumbing systems, it is importantthat when the water pressure falls in a water piping system that vacuumtherein of any degree be prevented to prevent contamination being drawninto the water supply system. Practically all plumbing codes provide forsuch devices.

Since such a device may and usually does stay in the closed position forseveral months to a year or more, there is great danger that corrosion,or the natural tendency of rubber to stick to a valve seat, will allow avacuum of substantial degree to be established when a stop-andwaste cockis opened, when a fire engine makes a heavy draft on a hydrant in theneighborhood, or when any other of the quite numerous causes forreducing the water pressure shall occur.

Valves or seats of rubber or rubber composition seem to be the onlyalternative to ground joints, which are likewise prone to stick.

An object of the present invention is the employment of a valve thatstretches materially under the influence of pressure as it is forced toits seat so that the inherent resiliency of rubber will rip it looseagain should there be any sticking tendency.

Another object of the invention is a valve that normally falls open inthe absence of pressure so that it actually opens just before thepressure in the receptacle reaches atmosphere pressure.

A highly important object of the invention is to provide means fortrapping and hermetically sealing in a film of moisture, between therubber valve and its seat, over the greater portion of the area ofcontact, to prevent sticking.

Another object is a structure, principally of rubber, that is adapted tobe forced into position on a plurality of seats in such manner that eachand every small unit of surface that contacts a seat does so undertension, hence distorted, so that it will rip itself loose by thetendency of the rubber to return to its original shape when the pressurefalls, completing the process and completely counteracting any stickingtendency before the pressure against it has reached the atmospherepressure point.

Iattain the objects sought and others that will be apparent by thestructure illustrated in the accompanying drawing in four figures anddescribed in the subjoined specification.

In the drawing- Fig. I is a vertical section of my vacuum preventershown attached to a pipe nipple which will be presumed to be a part of awater supply system in a building;

Fig. II shows the same structure as Fig. I, partially in section, withthe single working part in a different position;

Fig. III is again the same structure shown in Figs. I and II with theworking part in the position it will take when no pressure above that ofthe atmosphere exists in the pipe system and no fluid is present; and

Fig. IV is a cross section on the line IVIV of Fig. I.

In the drawing, I is a body for attachment to a receptacle, such as thepipe nipple 2, that is provided with an interior valve containing space3. For convenience the body I is made in two parts, a base la. and a caplb. The body I is provided with an air inlet opening 4 and interiorly itis provided with a plurality of valve seats such as 6, l and 8.

A valve I0 is provided that is, in general form, an inverted cup ofrubber or other stretchable material having the well knowncharacteristics of rubber, the word rubber being used with thisinclusive meaning. Only a sectional view of the valve i0 is shown as itwill be symmetrical, hence is fully disclosed in the sectional view.

The valve l0 must be made as an inverted cup to realize the virtues ofmy present invention, but may otherwise vary in general outline. It ispreferred to be made as follows, as this is a very efliicient form, frompresent experience.

The valve comprises, a rim portion or bead Illa, having moulded withinit a metal ring lllb, sidewalls l0c that converge and finally join, anda top portion l 911 that is somewhat larger than the air inlet opening4. Imbedded in the top portion 10d, I prefer to place a disc of fabricllle, such as is commonly used in making diaphragm material, as is wellknown; or the top portion may be made stronger than the side walls Illcby being made thicker; or in any other or preferred manner so that it isstronger and less stretchable than the sidewalls.

By construction of the inverted cup valve in this manner the metalinsert IOb serves a double purpose, to prevent contraction of the rimunder stress of pressure and to weight the cup. By weighting the cup,water, when it enters the valve chamber, will reach a level above therim before the cup floats and a small quantity of water will be trappedabove the rim; then as pressure increases the top portion of the valve,indicated by Hill, will reach its seat I, somewhat before thestretchable sides Hlc are forced outwardly into contact with the valveseat portion indicated by 8; hence a film of water that has been trappedin the space above the rim Illa will be hermetically sealed in toeffectually prevent sticking.

The air inlet opening 4 may be divided into several separate holes butit is not as good.

It will be particularly noted that when unstretched, as shown in Fig.III, the sidewalls are of a different angle than the cooperating valveseat 8 with which they are to contact when under pressure. This isimportant.

Interiorly the base la is provided with multiple supports ls upon whichthe bead portion of the valve, Illa, rests when conditions are asdescribed for Fig. III. Also the interior space 3 is so formed that whenthe valve is placed in position between la and lb: it cannot becomedisplaced so that it will not operate properly when assembled in properposition as shown in the first three figures.

Upon access of liquid to the receptacle 2-and its flowing into the space3, air will be trapped underneath the inverted cup valve member It andit will float from the position shown in Fig. III to that shown in Fig.II as a first movement. The top of the bead lila will contact the valveseat 6 and make a fairly good seal if the valve has been properly made,the seal improving as pressure builds up.

There Will be a bulge of the reinforced top of the cup, as shown in Fig.I, due to pressure. This bulge will always pulsate, every time pressureis lowered due to draft of water, hence sticking at this point due tolong continued pressure is not to be expected.

Pressure in water supply systems is variable, affected by two things,pressure head and flow friction due to use, therefore the pressures arenever at rest at any point, for more than momentary intervals, hence mystretchable valve that stretches more with high pressure and restoresitself at low, will never be at rest when connected to such a system,and cannot stick since the sticking of a rubber valve to its seat is dueto chemical action requiring time.

It will be noted that the metal ring 582) is to all intentsincompressible when uniformly loaded as is provided for, but thematerial of the bead llla will give a bit under the load applied by thestretching of the sidewalls ltc so that when the valve as a whole is inthe position shown in Fig. I, each unit of valve surface that is incontact will be stretched to a greater or less degree.

When pressure starts to fall within the body l the inverted cup valveimmediately begins to restore itself to its original shape, not waitinguntil the pressure reaches that of the atmosphere. If it has stuck atany point, it will strip itself loose, progressively as the pressurefalls, until when the pressure reaches that of the atmosphere it iscompletely loose and ready to fall to the position shown in Fig. III.

Variations in shape are possible within limits, hence the drawing isused as illustrative and not as limiting. What I claim as my inventionis ..o be ascertained by the following claims.

1. A vacuum preventer, comprising a body providcd with an air inletopening, plurality of valve seats axially arranged adjacent the innerterminus of said opening and an inverted cup valve member having arelatively rigid perimeter and elastic cup walls that is adapted tocontact one of said plurality of valve seats under the influence ofinternal liquid pressure and be stretched into engagement with the otherseats of said plurality upon increase of internal pressure.

2. A vacuum preventer for receptacles comprising a body that is providedwith an interior valve containing space and an air inlet opening throughan outside wall, a plurality of valve seats interiorly arranged in saidbody in coaxially arranged relationship adjacent said opening and aninverted elastic cup valve member having a relatively rigid perimeterthat is adapted to contact the lowermost of said valve seats under theinfluence of liquid rising in the body and to be stretched intoengagement with the other seats upon accumulation of pressure of saidliquid.

3. In a vacuum preventer, a chamber provided with an air inlet, pluralvalve seats in the chamber that are axially arranged to cooperate with avalve for controlling the inlet and an inverted cup shaped valve havinga relatively rigid rim and elastic walls in cooperative relationship tosaid seats, the said valve being characterized by being arranged tocontact one of said valve seats first and to then be stretched intocontact with others of said seats.

4. In a vacuum breaker of the character described, a body member, achamber formed in said body member with convergent top walls and anaxial vent opening and a cup shaped rubber valve member supported belowthe top walls and vent that is adapted to float into engagementtherewith upon access of water therebeneath, the said cup shaped rubbervalve being characterized by a convergent top wall of lesser pitch thanthe mating wall of the chamber.

5. A stretchable valve for a vacuum breaker of the character describedcomprising a stretchable inverted cup shaped member provided with a topclosure made integral therewith, said top closure being reinforced, arelatively thin water impervious wall therebeneath, and a reinforcedvalve portion beneath the thin wall that is adapted to function as avalve against a circular seat, the whole being arranged to float thesaid valve portion into contact with a valve seat upon access of Watertherebeneath.

6. A vacuum preventer device comprising a body that contains a topvented chamber, a stretchable inverted cup shaped valve in said chamberthat is arranged to float into covering position with respect to thevent upon access of liquid therebeneath, said vented chamber having abroad valve seat below the vent that is so proportioned with respect tothe valve that its most distant part from the vent is contacted by thefloating valve first and the complete closure is eifected by the valvestretching into engagement with the remainder of the seat under theinfluence or liquid pressure.

'7. A vacuum preventer defined as a body member adapted for connectionto a water supply system and having a top vented chamber formed therein,an inverted cup shaped resilient valve in said chamber that is normallysupported below the vent and is adapted to float into closingrelationship therewith upon access of water therebeneath, said vacuumpreventer characterized by normally non-conforming internal surfaces inthe chamber and external surfaces on the in- 7 verted cup whereby thecup is forced to complete the closure by stretching into conformity uponaccess of water pressure therebeneath;

8. A vacuumpreventer comprising a hollow top vented body, means forconnecting the lower part of the body to a water supply conduit, acupshapcd valve of stretchable material in the hollow body that isnormally sustained below the vent and adapted to float upwardly uponaccess of water from beneath, the inner surface of said body beingcharacterized by a plurality of axially arranged valve seats sopositioned that the valve will contact the lowermost thereof first andbe stretched into contact with the higher undei influence of waterpressure inside the cup of the valve.

9. A valve body that is provided with a vertical inner chamberterminated by a convergent top wall that is provided with a central ventopening, an inverted cup-shaped valve member of stretchable material insaid chamber that is normally supported out of contact with the chamberwalls, the said inverted cup-shaped valve being adapted to float intocontact with a lower part of the convergent wall upon access of fluidtherebeneath and be stretched into contact with the upper portionthereof upon access of fluid pressure.

- vVICTOR W. STRODE.

